Pneumatic dispatch system



March 31, 1942. M. MBO-TTEMILLER PNEUMAT1C-DISPATCH s-YsTErQx Filed AMarch so, 1940 0 NOP ik l J .j g sa Y 21 -2. 2 L@ m.. 2K ...om @om Patented Mar. 3l, 1942 PNEUMATIC DISPATCH SYSTEM Merton M. Bottemiller, Minneapolis, Minn., as-

signor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application March 30, 1940, Serial No. 327,051

3 Claims.

The present invention relates to dispatch systems, and more particularly to a novel control arrangement for obtaining eflicient and economical control for such a system.

An object of this invention is to provide a control arrangement for a pneumatic dispatch system whereby the air impeller, or exhauster,'for causing air to iiow through the tubes between the several stations, will operate only so long as a carrier for messages, and the like, is in transit in any of the tubes.

Another object is to provide a unique control arrangement wherein an energizing circuit for a fan, or blower motor, is established upon inserting a carrier into the transporting tube at the sending station, the circuit for the motor remaining established only until the carrier reaches the receiving station. The circuit being broken by the carrier in leaving the tube.

A further object is to provide a pneumatic dispatch system wherein the controls are so adapted to units, or individual transporting tubes, that the various units may be installed so as to comprise a great number of stations or only two stations, as desirable for the particular needs of the user thereof; while not changing the various controls and wirings for each station.

Other objects will be in part obvious and in other parts pointed out in the specication, and in the claims.

For a complete understanding of the present invention reference is made to the accompanying detailed description wherein reference will be made to the accompanying drawing, in which Figure l diagrammatically shows a pneumatic dispatch system with my novel control arrangement incorporated therewith, and

Figure 2 shows a detail view of an inlet opening with a door and control switch therefor.

Referring more particularly to the drawing, the pneumatic transporting system shown therein comprises three sending and receiving stations, A being the master station and B and C being the remote stations. It will be understood that only two stations would need be utilized or that many more than three stations could be utilized if desired. It will also be clearly understood that other transporting means could be readily adapted to use with the present novel control arrangement to be hereinafter more particularly described.

From each of the stations there is a sending inlet and a receiving outlet for various tubes. For example, the tube Iii serves to transport a carrier from station A to station B, the tube II serves to transport a carrier from station B to station A. Tube l2 serves to transport a carrier from station A to station C. Tube I3 serves to transport a carrier from station C to station A.

To furnish a motivating force for the carriers when they are placed within the tubes, means are generally indicated at I5 for exhausting the tubes. The exhaust means comprises a fan I6 which is driven by an electric motor I1 which is intermittently operated by controls to be hereinafter more fully described. The fan I6 is connected to the tubes II and I3 by tube I8. Air is drawn into the tubes which connect stations A and B together through an inlet port 20 and air is drawn into the tubes which connect stations A and C through an inlet port 2|. The course of the air through the latter system when the fan is placed into operation is as follows. yAir enters the inlet 2| and is drawn through the tube I2 from whence its passes through a tube 22 which connects the tubes I2 and I3 back through the tube I3 to the tube I8 and the fan I6. The course of air through the system A, B is into the inlet port 20 through the tube I0, connecting tube 25, tube II, tube I8, and fan I6.

The various tubes are equipped with spring.

biased normally closed inlet and outlet doors which when closed, render the tube systems relatively air tight so that air will flow into the tubes only through the openings 20 and 2I. However, the inlet doors 30 and 35 may be provided with suitable holes to thereby obviate the need for the openings 20 and 2|. The tube I0 has an inlet door 30 at the station A and an outlet door 3l I at the station B. Likewise at station BI there is an inlet door 32 for the tube II and an outlet door 33 at station A. There is an inlet door 35 at station A for the tube I2 and an outlet door 36 at station C. Likewise there is an inlet door 3l at station C for the tube I3 and an outlet door 38 therefor at station A. Underneath the various outlet doors there are receiving baskets 40' located so as to receive a carrier which has passed through the tube and out of any of the outlet doors.

Each of the doors is equipped with a switch the details of which are shown in Figure 2 and which correspond to the inlet door assembly at station A. A mercury switch 4I is mounted within a block 42. This switch may be suitably cemented in the block. This block may be suitably secured to the door 30 which is hinged on the pivot 43. It is preferable that the block 42 be mounted relatively near the pivot 43 so that the switch 4I will not be unnecessarily jarrecl.

The electrodes Within the switch are adapted to be normally open when the inlet door is closed. It will be readily apparent that when the door 30 is rotated in a counter-clockwise direction around the pivot 43 to open the same the mercury within the mercury switch will bridge the electrodes therein. It will be noted that the outlet doors are all disposed vertically. For eX- ample, the outlet door 3l is shown with the electrode leads entering the bottom of the switch mounting 42. It will be apparent that the outlet door switches are adapted to. be normally closed whereas the inlet door switches are adapted normally to be opened for purposes to be here? inafter more fully described. rIt will be obvious that both the inlet and outlet doors may be differently arranged as long as the switches are arranged so that the inlet door switches areA normally open and the outlet door switches are normally Closed. It also will be understood that the switches could be mounted otherwisethan on the doors without departing from the spirit of the present invention.

A relay mechanism 5l) is adapted to control the operation of sendingk a carrier from the station A to station B. The relay 50 comprises a solenoid Winding 5| which pulls in a core 52 to cause switch blades 53 and 54 to engage their respective contacts 55 and 56. The relay 5B may drop out by gravity or spring means, not shown. Energy for this relay is supplied by a step down transformer B which comprises a highvoltage primary 6| and a low voltage secondary winding 52.

A rgelay 5ta, which is similar in all respects to the relay 5S, is adapted to control the motor Il for a sending operation from the station B to station A. Similarly, relays Ech and lc control the sending and receivingV operations between the stations A and C.

Operation Assuming now that an operator at station A desires to send a carrier through the tube IB to station B. When the operator opens the door 30 to insert the carrier, the electrodes within the mercury switch 4l will be bridged by the mercury. When these electrodes are bridged a circuit for the solenoid winding 5l of the relay 5i) will be established from the transformer secondary 62 as follows: through the conductor 65, the electrodes of the mercury switch mounted upon the door 35, the conductor G6, thesolenoid winding 5l and conductor B1 back toy the other side of the transformer' secondary. When this circuit is established energizing the solenoid 5I the contacts arms 5?@1 and 54 will be moved into engagement with their respective contacts 55 and 56. A motor circuit will then be established which can be traced from the line wires 'lilY and 'Il as follows: from the line wire ii) through the conductor 13, switch contact 56, contact, arm 54, conductor T4 to the motor l and back to the other line wire 1I. Hence it is seen that when the door 3i! is open to insert a carrier a circuit is established which Will initiate operation of the fan to cause the air to be exhausted from the various tubes il), il, l2, and l3to cause the carrier to be forced through Whichever tube it happens to be in by atmospheric pressure, which in this instance is tube I3.

In order that no timing means need be utilized to control the operation of the fan motor I1 and in order to obtain a minimum operating period, i. e., operation of the fan only so long as a carrier is within a tube, a maintaining circuit is established for the relay 50 and the fan motor I1 through the outlet door 3l. This maintaining circuit may be traced as follows: from the secondary 62 of the transformer B0 through the conductor 65, the conductor 15, through the normally closed mercury switch mounted upon the outlet door 3l, conductor 16, contact 55, contact arm 53, conductor 11, solenoid 5l and conductor 61 back to the secondary of the transformer 60. Hence it is seen that a circuit is established which is independent of the mercury switch carried by the inlet door 30, but dependent upon the continued closure of the contacts Within the mercury switch carried by the door 3l. When the carrier passes the door 3| this door will be caused to open to permit passage thereof and in opening the normally closed contacts of the mercury switch will be opened. When these contacts are open the maintaining circuit which kept the relay energized will be broken and the relay 50 will drop out to open contact 56 to stop the operation of the motor I1.

If an operator desires to send a carrier from station B to station A the carrier will be inserted into the tube by opening the door 32. This will establish a circuit from the secondary of the transformer through the conductor 80, conductor 8l, conductor 82, the normally open switch on the inlet door 32 which is now closed, conductor 83, solenoid winding 5m, conductor B5 and conductor 8B back to the other side of the transformer secondary. When the relay solenoid Sla is energized the contact arms 53a and 54a will be pulled into engagement with their respective contacts 55a and 56a. A circuit for the motor I'I will then be established from the line conductor 'llll through the` conductor 81, contact 56a, contact arm 54a, conductor 88, conductor 'I4 to the motor I'I and back to the other line wire 1|. A maintaining circuit independent of the normally open switch carried upon the inlet door 32 will be established as follows: from the secondary of the transformer 60 through the conductor 80, conductor 8i, conductor 90, through the normally closed switch carried by the outlet door 33, conductor 9|, contact 55a, contact 53a, conductor 11a, solenoid 5|a, conductor and conductor 86 back to the other side of the transformer secondary.

It is seen that each tube I 0 and H has an independent circuit and an independent relay therefor which establishes independent motor circuits to cause operation of the fan l5. Therefore if it should occur that a carrier is first inserted into thetube I0 and a second carrier is inserted into the tube H, the motor I'I will not be deenergized because of the prior delivery of the carrier in the tube I0 and thereby shut down the system leaving the other carrier somewhere in the tube l I. It is also seen that means areA provided, by using a contact on an inlet door to initiate a circuit and a contact on the receiving door for maintaining that circuit independently of the contact on the inlet door, whereby a saving in energy is effected because the motor I1 will not operate any longer than absolutely necessary to deliver the carriers placed in the tubes.

The circuits which control sending and delivery between the stations A and C are identical with those which have been explained for sending and receiving between stations A and B. Relays 50h and 50c are adapted to control the sending and receiving operations through the tubes I2 and I3. The relay 50h is connected by conductors 95 and 96 to the motor circuit, and the relay 50c is connected by the conductors 91, 98 to the motor circuit. Hence when either of the inlet doors 35 or 31 is opened a circuit will be established which will start the motor I1. When a carrier tube is placed within either of the tubes I2 and I3 the circuit will be broken when the carrier passes either of the outlet doors 36 or 38.

From the above description it will be apparent that the motor I1 will operate only so long as a carrier is in transit in any of the tubes I0, II, I2, or I3. Therefore it is seen, that by utilizing the present novel control system for a pneumatic dispatch system, that a substantial economy in motor operation is effected.

While I have shown a preferred embodiment of my invention it will be understood that many modications such as applying the present principle to several more stations than shown will occur to those skilled in the art, also various means of operating a motor circuit switch 4in connection with sending and receiving stations will occur to those skilled in the art. I therefore wish to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a pneumatic dispatch system comprising a plurality of delivery tubes having sending and receiving stations with normally closed inlet and outlet doors therefor, the combination of, air circulating means for causing air to iiow through the delivery tubes, a motor for operating said circulating means, a normally open first switch associated with each of the normally closed inlet doors, connecting means between said iirst switch and said motor so arranged that said switch will start operation of said motor when said inlet door is opened to insert a carrier, a maintaining switch associated with said connecting means for establishing a maintaining circuit independently of said rst switch when a carrier is in transit in the tube, and a normally closed second switch associated with each of the normally closed outlet doors, said second switch being in circuit with said maintaining switch so that the maintaining circuit will be broken by said second switch to stop said motor when the carrier passes through said outlet door.

2. In a pneumatic dispatch system comprising a delivery tube having sending and receiving stations with normally closed inlet and outlet doors therefor, the combination of, electrically operated air circulating means for causing air to flow through the delivery tube, an electrical circuit for said circulating means, a normally open rst mercury switch operatively connected with the inlet door for energizing said circuit when said door is opened to receive a carrier, a relay in said circuit, a maintaining switch operated by said relay for establishing a maintaining circuit for said circulating means independently of said rst switch when a carrier is in transit in the tube, and a normally closed second mercury switch operatively connected to said outlet door, said second switch being in circuit with said maintaining switch so the maintaining circuit will be broken by said second switch to deenergize said circulating means when the carrier passes through said outlet door.

3. In a pneumatic dispatch system, in combination, a delivery tube having sending and receiving stations, normally closed inlet and outlet doors for said tuloe, electrically operated air circulating means for causing air to flow through said tube, a high voltage electrical circuit for said means, a first switch in said circuit; a transformer for providing a circuit of low voltage, a relay in said low voltage circuit for operating said first switch to energize said circulating means, a normally open second switch operatively connected with said inletdoor for energizing said relay when said door is opened to receive a carrier, a maintaining switch in said low voltage circuit operated by said relay simultaneously with the operation of said first switch for establishing a maintaining circuit for said circulating means while a carrier is in transit in said tube, and a normally closed third switch operatively connected to said outlet door, said third switch being in series circuit with said maintaining switch s'o the maintaining circuit will be broken by said second switch to deenergize said circulating means when the carrier passes through said outlet door.

MERTON M. BO'II'EMILLER. 

